As shown in FIG. 1, the conventional PDC system usually comprises a control box 71, multiple sensors 72, at least one reminder 73, the multiple sensors 72 are respectively connected to the control box 71 and coordinate with each other under the control of the control box 71, wherein, each of the multiple sensors 72 separately detects and transmits the data of any obstacle to the control box 71 for processing. The control box 71 analyzes the data and judges the distance and orientation of the obstacle. When the distance of the obstacle meets the designated conditions, the control box 71 informs the reminder 73 and gives out an alarm. The multiple sensors 72 are set on the external sides of the vehicle body according to demands, for example, front and rear bumpers, and the control box 71 is set in the vehicle. The signal transmission and power supply feed between the multiple sensors 72 and the control box 71, etc. are very complex, not only increasing the cables and the cost of the control box 71, but also causing interference due to too long data cable, because about 4 sensors 72 will usually be used and set at a certain interval.
To address the above problem, a PDC system without host is developed. For details, please refer to Chinese patent CN1892249A. As shown in FIG. 2, it comprises at least one master sensor and one or more slave sensors 82. The master sensor 81 has the obstacle detection function and coordinately controls working sequence of the slave sensors 82; by virtue of its obstacle detection function via the master sensor 91 and coordinated control over working sequence of the slave sensors 82, the control box 71 is substituted, thus eliminating the effect of the control box 71; meanwhile, because the master sensor 81 and the slave sensors 82 are set on the bumpers, the whole PDC system can shorten the length of the data cable and realize test implementation on the bumper, thus increasing the vehicle test efficiency.
As shown in FIG. 3, the Chinese Patent CN102129076A developed by the Applicant to overcome the defect of the patent relates to a cascade-structure PDC system without host, comprising multiple sensors 91, wherein the first terminal of each of the multiple sensors 91 is connected to the second terminal of the adjacent sensor 91 via internal network 92 to form a cascade structure and realize information transmission among the multiple sensors 91. The system is characterized by high response efficiency, high production and installation efficiency and high radar accuracy.
Nevertheless, in the above two patents, either the master sensor 81 and the slave sensor 82 in Chinese patent CN1892249A or the multiple sensor 91 in Chinese patent CN102129076A comprises respectively a microprocessor, i.e. each sensor is a digital probe with CPU, thus causing a high cost.
As shown in FIG. 4, Chinese Patent CN103592649A developed by the Applicant continuously to overcome the defect of the patent relates to an integrated PDC system, comprising a master sensor and at least one slave sensor, wherein, the master sensor 1 comprises a CPU module 11, a first ultrasonic transducer 12, a master drive module 13, a master amplifier module 14 and at least one slave drive module 15. In the CPU module 11, an A/D conversion module is provided. The CPU module 11 drives the first ultrasonic transducer 12 via the master drive module 13. The first ultrasonic transducer 12 amplifies and transmits echoed simulation signals to the A/D conversion module of the CPU module 11 via the master amplifier module 14. Each slave sensor 2 is a simulation probe without CPU. The CPU module 11 drives a slave sensor 2 via a slave drive module 15; each slave sensor 2 transmits the echoed simulation signal to the A/D conversion module of the CPU module 11. Each slave sensor 2 comprises a boost drive module 21, a second ultrasonic transducer 22 and an amplifier module 23. The boost drive module 21 locates between the slave drive module 15 and the second ultrasonic transducer 22 for the secondary drive. The slave amplifier module 23 amplifies and transmits the echoed simulation signal to the A/D conversion module of the CPU module 11. The signal line and the power line between the master sensor and the slave sensor are integrated, i.e. current is also transmitted on the signal line and signal is also transmitted on the power line. The master sensor of the integrated PDC system serves as not only a controller but also a probe; at least one slave sensor only plays a role as a probe and is connected to the master sensor for communication, further making the whole PDC system realize all functions as same as the existing PDC system with or without host.
Nevertheless, the Applicant finds out that it can be further optimized, for example, such properties as capacity, detection distance (about 1.5 cm), energy, signal amplitude and anti-interference performance can be further improved.